All tools which use fasteners, such as rivets or the like, for various fastening operations, such as in the manufacture of aircraft, require a fastener feed system. Depending upon the tool, such a fastener feed system can be manual or it can involve various combinations and arrangements of mechanical and/or electro-mechanical assemblies which in one form or another automatically feed fasteners to the tool. In one specific example involving rivets, an apparatus known as a vibratory bowl is used to supply rivets to a high production riveting machine. With the vibratory bowl, a large number of fasteners is emptied into the bowl, with the fasteners being randomly distributed. The combined effect of the configuration of the vibratory bowl and the vibrating action results in the rivets being positioned end-to-end in single file at the outlet of the bowl. From the bowl, rivets are fed into an escapement line which in turn connects to a main rivet feed line to which a source of pressurized air is connected. The air moves the rivet at high speed in the main feed line, typically one at a time, to the riveting machine.
However, vibratory bowls have a number of disadvantages. One significant disadvantage is their size and weight. Since each size rivet requires a separate vibratory bowl, and since as many as thirty (30) different rivet configurations are necessary in a large scale assembly operation, thirty (30) bowls would be required for such a rivet feeding system. This requires a considerable amount of space relatively close to the riveting machine.
In addition, while vibratory bowls are generally reliable, in operation, they do from time to time have jamming problems, particularly where the rivets move from the bowl into the escapement line. In a complete assembly system using high speed automatic riveting equipment, all of the individual subsystems must be reliable for the overall system to perform well. While the use of vibratory bowls has had a negative effect on overall system reliability, there has been few if any viable alternatives to date with the vibratory bowl arrangement.
Hence, there is a significant need for a more reliable and more streamlined system for automatically feeding fasteners to a fastening tool such as a riveting machine.